The overall objectives of the Virology Core Laboratory are to provide comprehensive virologic tests and services relevant to HIV research, to make available its specialized BSL2/3 laboratory facilities to HW researchers, and to develop new virologic tests that may be useful in clinical and basic research. Major core services include: (1) assays of HW infectivity by means of quantitative micrococultures, (2) assays of HW1 RNA and DNA, (3) characterization of HIV quasispecies, (4) phenotypic characterization of drug resistance and of syncytium-inducing capacity, and (5) processing, storage and shipment of blood specimens and other biological samples from patients with HIV. The core will also provide training and technical advice to researchers interested in developing sophisticated virologic procedures for their HW projects.